Oxidoreductases were among the earliest enzymes to be recognized and utilize redox cofactors for novel biological transformations that include nitrogen fixation, oxidative bursts in neutrophils, DNA repair, and in a growing number of signaling processes that govern gene regulation and expression. This research will focus on the design, synthesis and characterization of redox protein maquettes capable of electron transfer reactions in order to understand the tenets governing protein electron transfer and coupled chemical reactions important to understanding biological activity. These redox proteins will be designed from natural proteins within a stable four-helix bundle structural motif. Porphyrin cofactors will be incorporated into heme binding sites and appended to the bundle periphery. Iron-sulfur clusters and photoactive cofactors will also be studied to develop methodologies for the insertion of multiple cofactors into the four-helix bundle framework as a basis for the construction of functional synthetic redox enzymes.